When Tobacco and Cannabis Use Motives Interact: Implications for Dependence and Quitting.

BACKGROUND: Tobacco and cannabis co-use is a major public health issue among young adults. Little is known about how motives for using these substances interact and affect co-use behaviors. This study explores these associations and identify distinct motivational profiles among young people who co-use. METHODS: A cross-sectional survey was conducted among 357 French young adults (18-30 years; 54.9% men) reporting co-use. Participants indicated (Yes/No) their endorsement of 21 motives (10 tobacco-related, 11 cannabis-related, 7 shared). Correlations were computed between all motives. Hierarchical clustering identified distinct motivational profiles. Associations between profiles, motives, dependence, and readiness to quit were examined using regression models. RESULTS: Most within-substance motives and all shared cross-substance motives were correlated. Three clusters emerged: (1) high tobacco/moderate cannabis motive endorsement (n = 188), with high nicotine dependence; (2) low overall motive endorsement (except pleasure) and low dependence levels (n = 39); and (3) high endorsement of both tobacco and cannabis motives, with high dependence levels (n = 130). The number of endorsed tobacco motives was negatively associated with readiness to quit tobacco but positively associated with readiness to quit cannabis. CONCLUSIONS: While tobacco and cannabis motives overlapped, these findings underscore the need to consider motivational patterns when designing tailored interventions to reduce co-use-related harms.